1. Field of the Invention
The present invention relates to image processing and pattern identification, and specifically to, a sky detection system used in an image collection device and a method using the sky detection system.
2. Description of the Related Art
Up until now, technologies for detecting sky with image collection devices such as cameras and image pickup devices have been developed. For example, Patent Document 1 has disclosed a method for detecting sky in an image. This method includes classifying potential sky pixels based on colors; extracting communicated regions from the potential sky pixels; calculating saturation-degree attenuation gradients of regions excluding those that have a texture above a predetermined threshold; and identifying the regions that have the attenuation gradients matching the predetermined threshold as true sky regions in the image.
Further, Non-Patent Document 1 has disclosed a method for detecting sky based on a physical model. This method includes a classification step based on colors; a region extraction step; and a sky signature identification step based on the physical model.
However, the above calculation methods for detecting sky are complicated and thus cannot be carried out in real time. In addition, these methods are based on only pixel information in images and do not substantially use effective information of an image collection device.
Patent Document 1: U.S. Pat. No. 6,504,951
Non-Patent Document 1: A physical model-based approach to detecting sky in photographic images, Jiebo Luo and Stephen P., IEEE Trans on Image Processing, 2000